The present invention relates to a solid state image pick-up device comprising a plurality of picture elements arranged in a matrix form, each having a MOS transistor and a photodiode, vertical and horizontal scanning lines for scanning the picture elements, vertical and horizontal shift registers for producing vertical and horizontal scanning pulses which drive the vertical and horizontal scanning lines, respectively, to read-out photoelectrically converted signal charge stored in the photodiodes onto a signal read-out line.
The solid state image pick-up device of the kind mentioned above operates under a so-called XY address system and has an electronic shutter function. Such a solid state image pick-up device can be manufactured by utilizing the well-developed MOS-IC technique and has been generally applied to small size video cameras.
FIGS. 1A and 1B illustrate an example of a known solid state image pick-up device. FIG. 1A shows schematically the whole construction of the device and FIG. 1B is a cross section depicting the construction of a single picture element. The image pick-up device comprises a number of picture elements 1-11, 1-12 . . . ; 1-21, 1-22 . . . ; . . . arranged in a matrix form and formed in a p-type semiconductor substrate 1. Each of the picture elements comprises a MOS transistor having a source 2 and a drain 4 formed in a main surface of the substrate 1 and a gate 3 formed on an insulating layer applied on the main surface, and a n.sup.+ p photodiode 5 constituted by a junction between the p-type substrate 1 and n.sup.+ source 2. In the source 2 is stored in signal charge whose amount corresponds to an incident light amount. To the gates 3 of the MOS transistors are applied vertical scanning pulses from a vertical shift register 6, while to the drains 4 of MOS transistors are connected horizontal selection switches 7-1, 7-2, . . . comprising MOS transistors and horizontal scanning pulses are applied to the switches from a horizontal shift register 8 so as to connect selectively the drains 4 of MOS transistors to a video output line V.L. The horizontal scanning pulse has a frequency f.sub.H of 15.75 KHz and the vertical scanning pulse has a frequency fv of 30 Hz.
When the vertical scanning pulse is applied to the gate 3 of MOS transister constituting a picture element and, at the same time, the drain 4 of the related MOS transistor is selected by a horizontal selection switch 7 driven by the horizontal scanning pulse, the signal charge stored in the photodiode 5 is read-out onto the video output line V.L. At the same time, the photodiode 5 is reverse-biased or reset by a supply source V.sub.D, so that the charge storing operation is started again.
In the known solid state image pick-up device explained above, the reading out operation and the reset operation are effected simultaneously, the charge storing period, i.e. the exposure time corresponding to a shutter open time is fixed to 1/fv=33.3 msec. and could not be made shorter than 1/fv.
In general, in case of picking-up a moving object, it is necessary to shorten the shutter open time in order to obtain a sharp image of the object. However, in the known pick-up device, since the shutter open time is fixed, when the moving object is picked-up, the image sharpness is decreased and the image quality becomes deteriorated to a great extent. In order to obviate such a drawback, it has been proposed to provide a high speed rotary shutter in a video camera or to ignite a stroboscopic lamp during a vertical blanking period. However, such a solution requires special devices, so that the camera is liable to be complicated in construction, large is size, heavy in weight and expensive in cost, and further usage of such a camera is limited in various ways.